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important questions for classification of periodic table class 10th
Answers
¶ What is meant by periodicity
in properties of elements with reference to the periodic table?
¶ Why do all the elements of the same group have similar properties?
¶ How will the tendency to gain electrons change as we go from left to right across a period? Why?
¶ any three limitations of Mendeleev’s classification.?
Question.1The elements of the second period of the Periodic Table are given below:
Li Be B C N O F
(a) Give reason to explain why atomic radii decrease from Li to F.
(b) Identify the most
(i) metallic and
(ii)non-metallic element.
Question.2(a) Why do we classify elements?
(b) What were the two criteria used by Mendeleev in creating his Periodic Table?
(c) Why did Mendeleev leave some gaps in his Periodic Table?
(d) In Mendeleev’s Periodic Table, why was there no mention of Noble gases like Helium, Neon and Argon?
(e) Would you place the two isotopes ‘ of chlorine, CI-35 and CI-37 in
different slots because of their different atomic masses or in the same slot because their chemical properties are the same? Justify your answer.
Question.3 Lithium, sodium and potassium form a Dobereiner’s triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.
Question.4 Chlorine, bromine and iodine form a Dobereiner’s triad. The atomic masses of chlorine and iodine are 35.5 and 126.9 respectively. Predict the atomic mass of bromine.
Question.5 Why was the system of classification of elements into triads not found suitable?
Question.6 State Mendeleev’s periodic law. Write two achievements of Mendeleev’s periodic table
Question.7 (a) What is meant by periodicity
in properties of elements with reference to the periodic table?
(b) Why do all the elements of the same group have similar properties?
(c) How will the tendency to gain electrons change as we go from left to right across a period? Why?